The presence of pinholes in concrete flooring is often an indication of an industrial floor coatings failure. When the concrete surface is applied with a film of coatings, air is trapped between the surface and the coating. A chemical reaction to warm temperature causes trapped air to rise to the surface and force its way out, creating crater-like surface indentations or pinholes.
Furthermore, when liquid industrial floor coatings settle into the concrete's minute nooks and vents, air is displaced from these nooks and travel to nearby areas. When the displaced air has gathered enough force, it will eventually cause a mini-eruption to form pinholes.
The causes of pinhole formation should be identified, with the corresponding solution promptly undertaken, to address the problems caused by this unsightly blister-like signs of industrial floor coatings failure.
Working with Heat or Warm Temperature
One major cause of pinhole occurrence is warm temperature. When the concrete surface is warmed, whatever moisture trapped within the nooks and crevasses of the surface vaporizes. With no outlet to release the trapped air, a forcible ejection of the air will occur at any weak part of the industrial floor coatings, forming pinholes.
The solution to air entrapment is to simply avoid applying industrial floor coatings in warm conditions. Painting contractors usually work at lowered temperatures whenever possible, when the concrete surface to be coated is cooler. To do the opposite – install industrial floor coatings when the temperature is rising – will catalyze the occurrence of pinholes.
Even out the surface profile
Another cause of pinhole formation in concrete floorings is the natural characteristics of concrete, which is uneven and irregular. The degree of uneven surface profile in concrete can even vary with the quality of the concrete mixture. Since aggregates are often thrown into the concrete mixture, such as sand, gravel or slag and ash, concrete is not one whole block of solid material. It is actually filled with near-invisible holes and minuscule irregularities that make for a rougher profile.
This rough profile traps more air during industrial floor coatings application. More trapped air will eventually seek an outlet when displaced by a film of coatings, and if the combined air has generated enough force to break free from the surface, this is when blisters or pinholes appear.
The solution to the uneven surface profile is to perform abrasive blasting as part of surface preparation, to smoothen the irregular surface as much as possible, and lessen the existence of air pockets in the surface. Another action that can be taken is to soak the surface with water before actual coating, to displace air ahead of time. There are also concrete-fortifying epoxies that can be applied prior to coating, which can also displace air by forming a crystal-like tight seal on the concrete surface.
Tame that displaced air
There are also several solutions that involve working with the behavior of trapped air. One is to reinforce the concrete floorings with epoxy sealers that penetrate the uneven surface and allow trapped air to be vented out. When the air bubbles erupt outward, the thin epoxy coatings will act to reseal the surface.
Another solution is a layered approach wherein a quick coating is first applied to random areas in the surface. The trapped air will seek outlet into the uncoated areas. The next layer of industrial floor coatings will now have a lesser amount of trapped air, lessening the chances of pinholes.
Another solution to avoid pinholes is to simply prevent trapped air from ever being expelled into the surface. This is achieved by applying industrial floor coatings that are very thick and extremely strong, tightly sealing whatever air is trapped during coating application.
When care is taken to prevent the occurrence of pinholes, the end-result of a blister-free, high-performing industrial floor coatings system is not that hard to attain.